I think someone else already answered it, but yes you are able to enter AE preferences while on a freeze. You can even be awarded an AE, just not one that requires qualification training. This means you can change bases on your current equipment, just not be awarded different equipment. There are a few exceptions to this. One is being awarded your first captain seat while still on a freeze. In this case, they will just add your remaining freeze to your new 2 year freeze.